Lymphoblastoid cell lines derived from normal individuals and lymphoma lines derived from Burkitts' lymphoma biopsies both express Epstein-Barr virus antigens but differ in their sensitivity to alkylating agents and to incorporated H3 in the presence of bromodeoxyuridine as well as in their cloning efficiency in semi-solid agar. The Burkitts' derived lymphoma lines have higher cloning efficiency and are more resistant to radiation. We propose to investigate the repair capabilities of the different lines considering both excision and other repair pathways and to determine whether the differences in sensitivity of the lines to agents which damage DNA can be related to differences in the content of cytoplasmic DNA in a manner analogous to the action of the resistance plasmids of some bacteria. We plan to study the differences in clonability of the lines by a long term experiment in which lymphoblastoid lines are treated repeatedly with two different mutagens and tested, after expression, for the production of high cloning lines. Such experiments should help determine whether the differences between the lymphoma and lymphoblast lines are genetic or due to some other factor. BIBLIOGRAPHIC REFERENCES: Strauss, B. 1976. Repair of DNA adducts produced by alkylation. in (Smith, E. ed.) Aging, Carcinogenesis and Radiation Biology. The Role of Nucleic Acid Addition Reactions. Plenum Press, N.Y. pp. 287-314. Scudiero, D., Norin, A., Karran, P. and Strauss, B. 1976. DNA Excision-repair deficiency of human peripheral blood lymphocytes treated with chemical carcinogens. Cancer Research 36: 1397-1403.